This invention relates to trimming component leads on the underside of printed circuit boards and more particularly to apparatus for rendering warped circuit boards more nearly flat as they pass over the leading edge of a rotating cutting disk for trimming component leads thereon.
Assembly of printed circuit (PC) boards includes inserting component leads into holes in the circuit board with the leads extending past the underside thereof. These partially assembled circuit boards can then be loaded into a conveyor and passed through a flow-solder machine to complete electrical and mechanical connections of components in the printed circuits. In an automated assembly process, the conveyor may carry the boards directly from the flow-solder operation to an automatic lead trimmer which cuts excess length from the component leads. A typical lead trimmer comprises one or more cutting disks which are located parallel to and a prescribed distance below the underside of the circuit board in the conveyor. It has been found that either through adverse storage conditions, heat during the soldering operation, the large width of a particular board, or initial manufacturing of the laminates of a board, that some boards are either permanently warped or will become warped in the conveyor. In some instances, the underside of the cutting disk will contact and damage printed circuitry on the underside of a warped board and/or the board itself.